1. Field of the Invention
The present invention relates to an image processing system such as a print system for use in a copying machine, a printer and the like, and also relates to an image processing method.
2. Description of Related Art
In a print system as one of image processing systems, image data sent from an image scanner, a personal computer and other equipments is written into a memory such as a DRAM (Dynamic Random Access Memory) after being stored in a hard disk or without being stored in a hard disk. The written image data is read out from the memory, and then is subjected to an image processing to be printed.
Generally, image data of a plurality of pages is written into a DRAM in a compressed state at a compression rate of from 100% to 5% depending on the original attributes. For example, the compression rate of image data of a page including many characters, is excellent. On the other hand, the compression rate of image data of a page including a large amount of half tones such as a picture, is poor.
Furthermore, as an image processing mode, an electronic sort mode and a memory recall mode are known. In the electronic sort mode, a processing of reading out image data from a DRAM in a predetermined page order, for example, page 1 to page N→page 1 to page N→ . . . , and printing the image, is repeated a plurality of times. In the memory recall mode, image data of an image once printed is held in a memory such as a DRAM or a hard disk. Thereafter, the image data is read out from the memory again based on, for example, a re-print request of a user, and printed.
As one example of a prior art of an image processing system disclosing a part of the aforementioned structure, Japanese Unexamined Laid-open Patent Publication No. H10-304111 is known. According to this prior art, in writing image data into a DRAM, in cases where empty capacity of a DRAM becomes smaller than an average capacity of image data of one page during a storing of image data of page n+1 into the DRAM after the completion of storing image data of page 1 to page n, the image data of page n+1 is stored, and then the subsequent processing is executed. In other words, from the earlier page, i.e., from page 1, among pages from page 1 to page n+1 in which image data is stored, the image data is discarded from the DRAM to secure empty capacity of the DRAM in turn. Then, the image data of page n+2 and the subsequent pages are stored in the empty area of the DRAM to continue printing operations.
However, in the aforementioned conventional image processing system, when it becomes impossible to secure a predetermined empty capacity of the DRAM, or it becomes insufficient to secure the empty capacity thereof, during the storing of the image data of page n+1 into the DRAM, even if it is possible to store the image data of page n+2 into the DRAM because the image size is actually smaller than the expected size, it requires to discard the image data of from page 1 from the DRAM in turn to secure an empty capacity of the DRAM. Therefore, it is necessary to hold an transmission of the image data from an image scanner or a personal computer, or to suspend the processing of the image data.
Such drawbacks do not always occur only in a print system but may occur in other image processing systems.